1. Field of the Invention
The present invention relates to the field of data processing systems. More particularly, the invention pertains to a media element library which allows a user to easily access a media element inside a magazine of media elements without having to remove the magazine from the media element library. In one advantageous embodiment, the media elements are tape cartridges.
2. Description of the Related Art
Magnetic tape cartridges, magnetic disks and optical disks are all widely used as peripheral memory storage devices for computer systems. Large computer systems often operate in conjunction with external libraries of several, dozens, or even hundreds of such media elements. Although originally such media elements were selected and loaded manually, automated libraries were developed to expedite the handling of the media. These systems typically include robotics for accessing a desired media element, retrieving it from its storage position and loading it into an appropriate reader.
As data storage requirements for computer systems have increased from megabytes to gigabytes to terabytes, the development of automated media libraries has received considerable attention. Some embodiments of magnetic tape libraries comprise a small number of magnetic tape cartridges, 5 to 15 being typical, and one or two tape drives housed in a single enclosure. Cabinet and even room-sized systems have also been developed which hold a much larger number of tapes and drives and which further comprise robotic arms, usually translatable on all three axes, which remove tapes from storage and place them in tape drives.
Security of the physical media elements is of concern in these libraries. Generally, automated tape libraries are locked enclosures or cabinets, allowing complete access to the media elements stored inside only to users with the appropriate key or password. However, it is often desirable to allow limited access to media elements to other, lower level users of the system. In these cases, xe2x80x9cmail slotsxe2x80x9d have been provided which receive individual media elements or groups of media elements from the internal robotic transport mechanism and route them outside the enclosure through the mail slot. Use of the mail slot may itself be limited to users having particular passwords, and system control software may dictate what media elements are available through the mail slot to various users having these passwords. For example, the system administrator may have access to the entire cabinet, while lower level clerks have access only to the mail slot to place blank tapes into the library, or to retrieve selected media elements from the library one or a few at a time. Users not given passwords by the system administrator may be able to store and retrieve data electronically, but will not be able to physically access any physical media elements in the library.
These prior art systems are complex and expensive to manufacture, requiring an independent transport path between a rack or magazine of media element storage locations and the mail slot. A data storage and retrieval system which allows a user to quickly add or replace tape cartridges without having to remove the magazine of media elements, without requiring complicated transport mechanisms, and without limiting system options for media access security has long been manifest.
In one embodiment, the invention comprises a media element library comprising a housing having a door, and a plurality of coupled media element storage locations forming a media element magazine. In this embodiment, at least a first media element storage location of the media element magazine is positioned relative to the door such that a media element in this storage location is accessible from outside the housing when the door is open. In addition, at least a second media element storage location of the media element magazine is positioned relative to the door such that a media element in this media element storage location is inaccessible from outside the housing when the door is open.
Methods of accessing media elements from media element libraries are also provided. In one embodiment such a method comprises delivering a media element to a cell of a media element magazine, moving the cell toward an opening in the media element library and away from other cells in the media element magazine, and removing the media element from the cell.
Media element magazines also are provided which may comprise a plurality of media element cells for storing media elements and a movable cell attached at one end of the media element magazine.